Recently, as polyesters and polyamides, typically represented by PET and nylon, have been widely used in manufacturing fibers, PET bottles, films and injection molded articles as plastic materials, a great amount of waste materials produced in a manufacturing process thereof and after use thereof raise environmental concerns. However, recycling amount and rate of such waste materials are very small and limitative. Currently, such waste materials are at most subjected to simple physical heat-melting treatment to produce secondary processed products or materials. Therefore, the resulting reclaimed products exhibit poor qualities, thus resulting in marked limitation of recyclability thereof. Furthermore, advanced industrial countries including the USA and Japan have effected strict environmental regulations, as a result, and to cope with such actions and trends, some companies have proposed products and methods of producing the same via recycling methods using chemical reaction. For example, reference may be made to U.S. Pat. Nos. 4,166,896, 4,223,068 and 4,417,001, and Japanese Patent Publication Laid-open Nos. Hei 5-311114, 6-9923 and 8-253596, all of which relate to a method of recycling a waste material containing polyester (PET) only. In particular, polyester/polyamide mixed products such as plastic bottles, composite molded articles and blended fibers are not recycled at all at present, raising major problems associated with disposal thereof, thus leading to an urgent need for solution to these problems. Further, no research into obtaining and manufacturing high functional materials has been conducted hitherto.